HIV screening

When to request this test

• Pregnant women: during antenatal care to prevent mother-to-child transmission
• High-risk patients: patients engaging in high-risk behaviors (sex workers, men who have sex with men (MSM), intravenous drug users, individuals with multiple sexual partners or inconsistent condom use)
• Clinical Indications: symptoms suggestive of HIV/AIDS, such as unexplained weight loss, chronic diarrhea, prolonged fever, or persistent opportunistic infections (e.g. tuberculosis or oral candidiasis)
• Post-Exposure situations: after potential exposure to HIV, such as unprotected sexual intercourse, needle-stick injuries, or sexual assault

Interferences & limitations

False-negative results: in rapid HIV tests can occur due to several factors, including limitations of the test itself or patient-related circumstances. The main causes are:

• Window period: during the early stages of HIV infection (acute infection), the viral load may be high, but antibodies (detected by most rapid tests) have not yet been produced (This period typically lasts 2-8 weeks but can extend to 12 weeks for some individuals)
• Test sensitivity: some rapid tests are less sensitive to certain HIV subtypes or strains prevalent in different regions, particularly in Africa where diverse subtypes exist
• Technical errors: improper sample collection, storage, or handling. incorrect test procedure or interpretation of results
• Immune suppression: in cases of advanced HIV/AIDS or co-existing immunosuppressive conditions, antibody production may be diminished, reducing test accuracy
• Antiretroviral therapy: early initiation of antiretroviral can suppress the immune response, potentially leading to undetectable antibody levels and false-negative results

False positive results: cross-reactivity with other antigens, autoimmune diseases.

A confirmation test (Western Blot) and a viral load is required to diagnose an active infection.

1 hour

• Sample nature: Serum
• Recommended volume: 2 mL
• Type of container: Serum tube , serum separation tube (SST)

<12h at room temperature